Tanning matter



Patented Sept. 20, 1938 TANNING MATTER Ernst Koch, Frankfort-on-the-Main-Hochst, Karl Dachlauer, Hofheim, and Christoph Thomsen, Frankfort-on-the-Main-Hochst, Germany, assignors to LG. Farbenindustrie Aktiengosellschaft, FrankIort-on-the-Main, Germany No Drawing. Application December 28, 1936, se-

rial No. 117,968. In Germany October-'3, 1935 4 Claims.

The present invention relates -to tanning matters.

We have found that tanning matters may be obtained from materials containing lignin by materials. It is also possible to impart to the tanning materials a further plumping power by the addition of natural or artificial resins or sparingly soluble phlobaphenes of vegetable 5 treating them with halogen or agents giving oflE tanning materials p f y ees 5 halogen and rendering water-soluble the products di Y Y- p l y p res s or 6010- thus obtained by treating them with salts of the ph ny res ns r t sp y 'p tlons of sulphurous acid in the presence or absence of quebracho). aldehydes. The alkali metal salts of the products may be As materials containing lignin there may, for obtained ,by evaporating the aqueous solution, 10 instance, be used wood, bark and the residue f likewise the free acids after a previous acidificathe saccharificatio of wood. These materials tion of the solution. If necessary the solid final are treated with halogen preferably either in an p d ct is Washed. The salts'as well as the free aqueous, alkaline, neutral or acid suspension oracids are brown -hygroscop c p he in an organic liquid which under the conditions free acid showsthe tanning action described. 15 of test does not react with halogen. The ma- The following examples serve to illustrate the terial containing lignin may also be moistened invention, butthey'are not intended to limitit with water or steam and then be treated with thereto, the parts being by weight:

. gaseous halogen which, if required may be diluted I o a Suspension Of 250 Parts Of cchariby'an inert gas. The preparation of ehicmfication residue (obtained by the treatment of 20 lignin is known (see Fuchs, Chemie des Lignin. l s of pine wood wit concentrated yd opage 97). chloric' acid) in 500 parts of water gaseous chlo- The material entirely or incompletely treated rine is i troduced at 10 C.-15 C. until saturawith halogen is then treated, if required after t n is attainedh Whole s then fi t d,

t has b separated from the suspending agent washed and the residue is dried. About 280 25 and sufliciently washed, in an aqueous suspenp s of r n n re Ob ained. sion with a watersoluble salt of the sulphurous 100 parts of this chloro-lign i 250 Parts of acid, such as sodium sulphite, potassium sulphite, water are first mixed with 5 parts of caustic sodium bisulphite, ammonium sulphite, ammosoda. 20 parts of a formaldehyde solution of 30 nium bisulphite and others. The reaction is ac-. per cent. strength are then added and the whole 30 'celerated by heating the material to a temperas h ed within one hour to about 95 C. 50 ture up to about 100 C. In som cases it may parts of sodium sulphite are then added and the be advantageous previously to neutralize the ture is s rred f r 6 hours at 95 C. The

-halogen hydracid which may be present. If in product is then soluble in water to a clear soluthis case an excess of alkali is added, the salt of tion, even after having been acidified with acetic 35 sulphurous acid may be obtainedby introducing acid. gaseous sulphurous acid. Furthermore,. on ren- ,It calf pelt is tanned with this acidified soludering watersoluble the halogenated material an tion, a l ght-brown, P p leather 15 Obta addition of aldehydes, such as formaldehyde or (2) 50 parts o t chloro-lignin Obtained a0- 40 acetaldehyde, is often advantageous. It is also r ng to Exam 1 e h d f r 8 hours to 40 possible, during .or after the rendering water- 5 C- n 1501391118 Of Water together with 30 soluble, to condense the product of halogen and parts of sodium sulphite. A brown solution withlignin with other compounds, for instance aroout any residue is obtained. If this solution is matic hydroxy compounds, or the sulphonic acids T acidified with sulphuric acid until a pH value of thereof, it necessary with the aid of aldehyde. ;3.5 is attained and animal skin is tanned with 45 The quantity of the salt of suliurous acid may this liquor, there is obtained a light-brown vary, it amounts at least to about half the weight leather of a good firmness and solidity. of the dry chloro-lignin. (3) 25 parts of the chloro lignin obtained ac- The products obtained remain watersoluble cording to Example 1 in 75 parts of water are also after having been acidified and in the acid" mixed with 1.5 parts of caustic soda, 20 parts of 50' condition they are good tanning materials. The formaldehyde solution of 30 per cent. strength leather tanned therewith is of a light-brown and. 15 parts of sodium sulphite are then added, color, full-bodied and of an excellent firmness the mixture is gradually heated to 95 C. and and solidity. The tanning materials may be'used stirred until the whole has been dissolved. The as such or in combination with other tanning solution is then acidified with oxalic acid. If

cow pelt is tanned with the acidified solution a leather is obtained having the same properties as that of Example 1.

(4) 500 parts of pine bark dried by exposure to air are freed from the tanning material by extracting them with cold and hot water. 390 parts of residue (dried) remain. Into' a suspension 'of 100 parts of this residue in 200 parts of water chlorine is introduced at 5 C. until saturation is attained. The whole is filtered and the residue in 250 parts of water which has been washed is mixed with parts of sodium sulfite and parts of formaldehyde solution of 30 per cent. strength. The mixture is heated in the course of 1 hour to C. and stirred at this temperature for 8 hours. The non-dissolved'cellulose is removed by filtration and the filtrate is acidified with sulfuric acid until a pH value of 3.0 is attained. If calf pelt is tanned with this tanning liquor, a light-brown leather of quebracho character is obtained.

(5) Chlorine is introduced, at 10 C.-20 C., into a suspension of 900 parts of hydrochloric lignin in 1500 parts of water until saturation is attained. The chloro-lignin obtained is then filtered with suction and washed. There are obtained 1740 parts of moist chloro-lignin contain- -ing'43 per cent. of water;

440 parts 0! this moist chloro-lignin are suspended with 300 parts of water and 300 parts of caustic soda solution of 10 per cent. strength and the suspension is then mixed with 250 parts of sodium sulfite. while stirring. The .whole is heated within 1 hour to about. 100 C. and stirred for 5 hours at this temperature. By an acidification with sulfuric acid and oxalic acid until a 7 About pH value of about 3.0 is attained there is produced a tanning material with the aid of which calf pelt and cow pelt is rapidly and uniformly tanned.

We claim:

1. The products obtainable by causing a watersoluble salt of sulfurousacid to act in an aqueous solution upon chloro-lignin, said products being in the form of their free acids brown and nonhygroscoplc. powders showing a tanning effect upon animal'skin.

2. The products obtainable by causing a lower aliphatic aldehyde and a watersolubie salt of sulfurous acid to act in an aqueous solution upon chloro-lignin, said products being in the form of their free acids brown and non-hygroscopic powders showing a tanning efiect upon animal skin.

3. The product obtainable by causing sodium sulfite to act upon chloro-lignin in an aqueous solution in the presence of sodium hydroxide at a temperature oi about 100 C. and acidifying the mixture, said product being in the form of its free acid a brown and non-hygroscopic powder showing a tanning efiect upon animal skin.

4. The product obtainable by causing sodium sulfite and formaldehyde to act upon chloro-lignin and aqueous solution at a temperature of about 100 C. and acidifying the mixture, said product being in the form of its free acid a brown and non-hygroscopic powder showing a tanning efi'ect upon animal skin.

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